Known methods of transferring drive from engines and motors to gearboxes, pumps, alternators, generators and compressors is accomplished by various forms of physical coupling including pulley belts, chains, gears, disks, cogs, diaphragm and viscous fluid type couplings. There are many problems associated with mechanical couplings, such as the requirement for periodic lubrication of gears, close alignment requirements of disc, diaphragm and hydraulic couplings and the limited life of elastomer and rubber element couplings. Energy losses in the form of friction and heat loss can be considerable in such apparatus.